#include "dusk/audio/DuskAudioSystem.h"

#include <SDL3/SDL_init.h>
#include <array>
#include <cassert>
#include <fstream>
#include <ios>
#include <span>

#include "JSystem/JAudio2/JASAiCtrl.h"
#include "JSystem/JAudio2/JASChannel.h"
#include "JSystem/JAudio2/JASCriticalSection.h"
#include "JSystem/JAudio2/JASDSPChannel.h"
#include "JSystem/JAudio2/JASHeapCtrl.h"

#include "DuskDsp.hpp"
#include "JSystem/JAudio2/JASAudioThread.h"

// #define DUSK_DUMP_AUDIO

using namespace dusk::audio;

static OutputSubframe OutBuffer;
static std::array<f32, DSP_SUBFRAME_SIZE * OutputSubframe::NUM_CHANNELS> OutInterleaveBuffer;

static SDL_AudioStream* PlaybackStream;

/**
 * SDL audiostream callback to trigger rendering of new audio data.
 */
static void SDLCALL GetNewAudio(
    void*,
    SDL_AudioStream*,
    int needed,
    int);

/**
 * Render an entire new frame of audio and output it to SDL3.
 * Note: "audio frames" are unrelated to video frames.
 * @return Amount of audio samples rendered.
 */
static int RenderNewAudioFrame();

/**
 * Render an audio subframe and output it to SDL3.
 */
static void RenderAudioSubframe();

static void InitSDL3Output() {
    SDL_Init(SDL_INIT_AUDIO);

    constexpr SDL_AudioSpec spec = {
        SDL_AUDIO_F32,
        2,
        SampleRate,
    };
    PlaybackStream = SDL_OpenAudioDeviceStream(
        SDL_AUDIO_DEVICE_DEFAULT_PLAYBACK,
        &spec,
        &GetNewAudio,
        nullptr);
}

void dusk::audio::Initialize() {
    InitSDL3Output();
    DspInit();

    JASDsp::initBuffer();
    JASDSPChannel::initAll();

    JASPoolAllocObject_MultiThreaded<JASChannel>::newMemPool(0x48);

    SDL_ResumeAudioStreamDevice(PlaybackStream);
}

void SDLCALL GetNewAudio(
    void*,
    SDL_AudioStream*,
    int needed,
    int) {
    while (needed > 0) {
        const int rendered = RenderNewAudioFrame();
        needed -= rendered;
    }
}

#if defined(DUSK_DUMP_AUDIO)
static std::ofstream outRaw("guh.raw", std::ios_base::out | std::ios_base::binary);
#endif

int RenderNewAudioFrame() {
    JASCriticalSection section;
    const u32 countSubframes = JASDriver::getSubFrames();

    JASAudioThread::setDSPSyncCount(countSubframes);

    for (u32 i = 0; i < countSubframes; i++) {
        RenderAudioSubframe();

        JASAudioThread::snIntCount -= 1;
    }

#if defined(DUSK_DUMP_AUDIO)
    outRaw.flush();
#endif

    return static_cast<u16>(countSubframes) * DSP_SUBFRAME_SIZE;
}

static void InterleaveOutputData(const OutputSubframe& data, std::span<f32> target) {
    assert(target.size() >= data.channels[0].size() * OutputSubframe::NUM_CHANNELS);

    size_t outPos = 0;
    for (size_t inPos = 0; inPos < data.channels[0].size(); inPos++) {
        for (size_t channelIdx = 0; channelIdx < OutputSubframe::NUM_CHANNELS; channelIdx++) {
            target[outPos++] = data.channels[channelIdx][inPos];
        }
    }
}

void RenderAudioSubframe() {
    OutBuffer = {};

    JASDriver::updateDSP();
    DspRender(OutBuffer);

    InterleaveOutputData(OutBuffer, OutInterleaveBuffer);

#if defined(DUSK_DUMP_AUDIO)
    outRaw.write((const char*)OutInterleaveBuffer.data(), sizeof(OutInterleaveBuffer));
#endif

    SDL_PutAudioStreamData(PlaybackStream, &OutInterleaveBuffer, sizeof(OutInterleaveBuffer));
}